A pumping element for a hydraulic pump is provided. The pumping element includes a cylinder forming a compression chamber and having a discharge port. A piston having a pressure surface, a spill port, and a passageway connecting the pressure surface with the spill port is disposed in the cylinder for reciprocal movement between a first position and a second position. The pressure surface of the piston is adapted to increase the pressure of a fluid disposed in the compression chamber as the piston moves between the first position and the second position. The pressurized fluid flows through the discharge port of the cylinder. A metering sleeve is disposed around the piston and is configured to selectively cover the spill port as the piston reciprocates between the first and second positions. The metering sleeve has a groove that is adapted for fluid communication with the spill port as the piston reciprocates between the first and second positions.